STATVFS(5)

NAME
statvfs - file system statistics

SYNOPSIS
#include <sys/types.h>
#include <sys/statvfs.h>

DESCRIPTION
The <sys/statvfs.h> header defines the structures and functions that return information about a mounted file system. The statvfs structure is defined as follows:

    typedef struct { int32_t val[2]; } fsid_t;	/* file system id type */
    #define VFS_NAMELEN  32 	/* length of fs type name, including nul */
    #define VFS_MNAMELEN 1024	/* length of buffer for returned name */
    struct statvfs {
    	unsigned long	f_flag;	  /* copy of mount exported flags */
    	unsigned long	f_bsize;  /* system block size */
    	unsigned long	f_frsize; /* system fragment size */
    	unsigned long	f_iosize; /* optimal file system block size */
    	/* The following are in units of f_frsize */
    	fsblkcnt_t	f_blocks; /* number of blocks in file system */
    	fsblkcnt_t	f_bfree;  /* free blocks avail in file system */
    	fsblkcnt_t	f_bavail; /* free blocks avail to non-root */
    	fsblkcnt_t	f_bresvd; /* blocks reserved for root */
    	fsfilcnt_t	f_files;  /* total file nodes in file system */
    	fsfilcnt_t	f_ffree;  /* free file nodes in file system */
    	fsfilcnt_t	f_favail; /* free file nodes avail to non-root */
    	fsfilcnt_t	f_fresvd; /* file nodes reserved for root */
    	uint64_t  f_syncreads;	  /* count of sync reads since mount */
    	uint64_t  f_syncwrites;	  /* count of sync writes since mount */
    	uint64_t  f_asyncreads;	  /* count of async reads since mount */
    	uint64_t  f_asyncwrites;  /* count of async writes since mount */
    	unsigned long	f_fsid;   /* POSIX compliant file system id */
    	fsid_t          f_fsidx;  /* NetBSD compatible file system id */
    	unsigned long	f_namemax;/* maximum filename length */
    	uid_t		f_owner; /* user that mounted the file system */
    	uint32_t	f_spare[4]; /* spare space */
    	char	f_fstypename[VFS_NAMELEN]; /* fs type name */
    	char	f_mntonname[VFS_MNAMELEN]; /* directory on which mounted */
    	char	f_mntfromname[VFS_MNAMELEN]; /* mounted file system */
    };

The f_flag argument can have the following bits set:

ST_RDONLY
    The filesystem is mounted read-only; Even the super-user may not write on it.

ST_NOEXEC
    Files may not be executed from the filesystem.

ST_NOSUID
    Setuid and setgid bits on files are not honored when they are executed.

ST_NODEV
    Special files in the filesystem may not be opened.

ST_UNION
    Union with underlying filesystem instead of obscuring it.

ST_SYNCHRONOUS
    All I/O to the filesystem is done synchronously.

ST_ASYNC
    No filesystem I/O is done synchronously.

ST_NOCOREDUMP
    Don't write core dumps to this file system.

ST_NOATIME
    Never update access times.

ST_SYMPERM
    Recognize symbolic link permission.

ST_NODEVMTIME
    Never update modification times for device files.

ST_LOG
    Use logging (journalling).

ST_LOCAL
    The filesystem resides locally.

ST_QUOTA
    The filesystem has quotas enabled on it.

ST_ROOTFS
    Identifies the root filesystem.

ST_EXRDONLY
    The filesystem is exported read-only.

ST_EXPORTED
    The filesystem is exported for both reading and writing.

ST_DEFEXPORTED
    The filesystem is exported for both reading and writing to any Internet host.

ST_EXPORTANON
    The filesystem maps all remote accesses to the anonymous user.

ST_EXKERB
    The filesystem is exported with Kerberos uid mapping.

ST_EXNORESPORT
    Don't enforce reserved ports (NFS).

ST_EXPUBLIC
    Public export (WebNFS).

Fields that are undefined for a particular file system are set to -1.

NOTES

f_flag
    The f_flag field is the same as the f_flags field in the 4.3BSD statfs(2) system call.

f_fsid
    Is defined to be unsigned long by the X/Open standard. Unfortunately this is not enough space to store our fsid_t, so we define an additional f_fsidx field.

f_bavail
    Could historically be negative (in the statfs(2) system call) when the used space has exceeded the non-superuser free space. In order to comply with the X/Open standard, we have to define fsblkcnt_t as an unsigned type, so in all cases where f_bavail would have been negative, we set it to 0. In addition we provide f_bresvd which contains the amount of reserved blocks for the superuser, so the old value of f_bavail can be easily computed as:

        	old_bavail = f_bfree - f_bresvd;

SEE ALSO
statvfs(2)

HISTORY
The <sys/statvfs.h> header first appeared in NetBSD 3.0.